I purchased 2 Galaxy S4's. After the end of the first year warranty, both stopped making calls at first intermittently then completely. With insurmountable difficulty they were approved for 'courtesy' repair under warranty by Samsung. I sent the phones to a certified Samsung repair shop. The service center then refused to repair both phones under warranty. They wanted $350 to repair one saying one was rooted (and the other had a cracked screen ....$650 to repair). I never root any phones nor had I cracked the screens. I asked for the phones back without any repairs. I then checked the phone with Connectbot and Root Checker and both show the phone is not rooted. (The phone with the cracked screen was now dead). Questions: Is the phone rooted and are these apps are wrong? If so how would it get rooted without me knowing(...I don't lone it out)? Does the certified service center have better tools to check for rooting? Could they have unrooted the phone without telling me? (My data and apps were on the phone when it was sent back).